The quotations in OED are the basis of its claim to scholarly and historical authority. The nineteenth-century founders of the dictionary set out to record every word in the English language by reading through all printed sources available to them (which were also, in various ways, appropriate for citation). Readers excerpted around five million quotations, from analysis of which the lexicographers constructed their definitions and traced semantic developments in the language. Two million quotations were published in the first edition (and a further 527,000 in the twentieth-century Supplement) to illustrate and provide evidence for this analysis. The quotations therefore play a crucial role in the OED, identifying the authorised users of the language and the connotations and nuances of the way words are actually used. (For more see Role of quotations).

But how were the sources chosen? And what sorts of quotations were used?